Humphree Stabilizer Clunking Noises
In 2023, we installed Humphree Stabilizers on Starr, our 77' Northern Marine trawler. They haven't been quiet!

In 2023, we installed Humphree Stabilizers on Starr, our 77' Northern Marine trawler. They haven't been quiet!
Humphree promised "ultra-quiet" and "ultra-silent" electric actuation.
At Anchor, our Humphree stabilizers are the opposite of ultra-quiet. Several times each night, they bang so loudly that they wake us from sleep. Guests have wondered if the boat hit something. The video clip above gives some sense of the banging.
Humphree promised a 4-year service interval on the main shaft seals.
Two years after initial installation, and less than a year after major factory service, seawater is leaking into the boat from the Humphree Stabilizers.
But as we used the boat, the clunking became more severe and more frequent. At anchor in Hawaii--admittedly difficult conditions--we were woken up several times each night by the banging noise. During the day, guests wondered what happened when the clunking occurred. It seemed like "sloppiness" in the gears or motor might be the cause, and we asked Humphree for help.
Humphree was initially responsive. They claimed they had other boats with similar problems. At one point they suggested a missing shim may be the cause. Other times they thought it was a software problem. After seven months of begging, they sent a crew to Hawaii to perform a fix.
For a few days, things were better. But the clunking quickly returned and is worse than ever. Humphree seems unwilling or unable to fix it.
Making matters worse, Humphree doesn't have dealers that are empowered to work on the system, and they don't provide owners with any resources for troubleshooting or repairing systems while cruising.
● After installation, Starr sails from Seattle to Hawaii.
● Infrequent banging, but loud clunk when "at-rest, bow-anchor" mode is engaged
● Clunking grows louder and more frequent, particularly in at-rest mode.
● The clunking can't be ignored anymore, and we reach out to Humphree for a solution.
● Humphree says it’s a missing bushing/shim and promises repair.
● After seven months of delays, Humphree replaced internal components and upgraded firmware.
● Robert (Supervisor), Esmir (Inventor/Engineer), and Dario (Sales) install new servo parts and software.
● Calm-water trial looks normal; problem declared fixed.
● On sea trial to Pokai Bay 2 weeks after Humphree declared everything (Perfect) in flat water, fins Bang and the boat shudders; head unit goes dark.
● At anchor, loud bangs hourly in zero-speed mode.
● Around midnight, fins shut down (no vessel power loss).
● New RCU, cables, head unit requested.
● The crew sends an email with a written report, video, and audio of more banging.
● Robert remotes in twice, changes firmware settings without explanation.
● Sea trials show little improvement.
● Morning: fins fail to activate underway. Esmir remotes in, changes settings, no explanation.
● Later: Humphree sends new RCU, head unit, and cables.
● At anchor in 1m swell, clunks occur in all modes.
● Recordings/data sent to engineers.
● Engineers find “activation zone” set to zero.
● Raising threshold reduces clunks but slows fin response.
● Display shows -88° trim, 20° angle.
● Humphree suspects internal tampering within the Humphree organization via an open server within their company where all the boats with Humphree units sit on.
● System reset and reprogrammed remotely.
● Fins activate in standby while tied in slip.
● Shut down immediately. Reported, but not acknowledged.
● Fins so dampened they respond sluggishly, with little stabilizing effect.
● Crew requests adjustments for passage.
● Fins perform well throughout crossing.
● Email reports banging persists, even in calm waters.
● Crew asks Humphree to program backup RCU and considers seismograph testing.
● Responds as if the issue is new, and ignores backup RCU requests.
● The system is fine, suggesting upgrading to new servos.
● We have gotten to a point where Humphree is non responsive and doesn't believe us.
● We have a PCE - VDR 10 vibration logger as well as an AEMC Voltage/Current Logger
● With these two pieces of equipment we are collecting verifiable visual data of the banging and shuddering of the fins.
● We are now 2 years in from when the initial problem was reported to Humphree, we are on a 4000nm trip from Fiji to Japan. The root problem has not been resolved and we suspect at this point that Humphree doesn't know what the problem is or how to fix it.
Our midship bilge alarm started going off sporadically, and after some searching (and the usual water-tasting test), we confirmed the water was salt. We traced it back to the port servo, where we found the vent tube for the outer lip seal was consistently pouring water out especially while under pressure when the fin was moving. So, it’s pretty clear that the shaft seals have failed.
Link for video of water coming out of vent tube.
We then packed grease into the Zerk fitting that’s designed for this purpose (it should be said that this was never mentioned to us, after some searching we did find a small excerpt not under troubleshooting but after the service and warranty pages and even then to replace or work on the seals it only makes reference to the “Workshop Manual”, something we don’t have but we would certainly like to have.) The zerk proceeded to take three full tubes of marine grease before it finally started coming out the vent tube.
Now our concern is whether water has made it into the main servo casing itself, possibly contaminating the planetary gears or the servo motor. If anyone has suggestions on how to check for water ingress in the main housing, we’d appreciate it.
This is a frustrating situation, especially considering we’ve done slightly over 9,000 miles in less than a year since Robert and Esmir completely replaced the inner workings (Planetary gears and motor) of the servos. Having to replace seals this often seems completely unreasonable for a system that’s supposed to be ocean-capable.
In regard to customer service, when we hauled the boat out before departing, we were told the system had an original manufacturing error, but we still paid the full bill of $6,340 for the haul-out. We were onboard watching and working on the boat daily during the repair, and based on what we saw, we strongly suspect that the external seals were never actually change, maybe because someone decided it wasn’t necessary. But given the current failure, if that was the decision, it seems extremely short-sighted.
We’re sharing this to connect with others and ask: Are we the only ones experiencing this kind of early failure, or is this a broader manufacturing issue with Humphree systems? We’d especially like to hear from operators of 100-ton+ vessels who’ve put offshore miles and weather extensively through their Humphree fins.
Humphree service has proven inadequate for a world-cruising boat. We waited nine months for the initial service, which didn't resolve the issue.
Zincs can only be changed after removing the fin. Gearbox oil can only be changed when hauled out. These systems were not designed for easy serviceability.
We have been cruising Starr, our 77' Northern Marine trawler since 2000, accumulating more than 100,000nm under the keel. In 2023, we removed the Naiad stabilizers and replaced them with Humphree stabilizers. The primary objective was quiet, generator-free stabilization-at-rest.
We want to talk with other Humphree Stabilizer owners! Do you experience any clunking noise? Have you been able to schedule service? Please reach out with your experiences, good or bad!
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